RESUMO
Tobacco plants were genetically engineered to express a detoxifying pathway for the herbicide phenmedipham. A gene from Arthrobacter oxidans strain P52 that encodes an enzyme catalysing the hydrolytic cleavage of the carbamate compound phenmedipham has recently been cloned and sequenced. The coding sequence was fused with a cauliflower mosaic virus 35S promoter and introduced into tobacco plants by Agrobacterium-mediated gene transfer. Transgenic plants expressing high levels of phenmedipham hydrolase exhibited resistance when sprayed with the herbicide at up to ten times the usual field application rate.
Assuntos
Carbamatos , Genes Bacterianos , Herbicidas , Resistência a Inseticidas/genética , Nicotiana/genética , Plantas Tóxicas , Arthrobacter/genética , Sequência de Bases , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Fotossíntese , Plantas Geneticamente Modificadas , Plasmídeos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Rhizobium/genética , Nicotiana/fisiologia , Transformação GenéticaRESUMO
The experimental infection of mice with Yersinia enterocolitica serotype O8 was investigated in a quantitative and histological study. The course of bacterial penetration and spreading was precisely determined by immunohistochemical staining. After oral administration, the bacteria passed the epithelial barrier of the ileum and spread into the lamina propria. By preference they entered Peyer's patches, which were about 1,000 times more heavily colonized than the surrounding epithelium of a comparable surface area. The bacteria proliferated in the follicles, from which they spread into the lamina propria of the villi. At either site most of the bacteria multiplied extracellularly, with only a small percentage observed to be present within the phagocytes. The bacteria did not appear to be able to pass the intact basement membrane; hence, the integrity of the basement membrane is likely to play a role in determining the route of entry and limit of spread of Y. enterocolitica infection.
